From cb4023855c5725d79f7b465715adad3ab11280bb Mon Sep 17 00:00:00 2001
From: Ian Davis <nospam@iandavis.com>
Date: Wed, 28 Jul 2021 13:08:52 +0100
Subject: [PATCH] Ensure read of alerts slice is performed while holding lock

Fixes data race:

==================
WARNING: DATA RACE
Read at 0x00c029ae7f10 by goroutine 4785:
  github.com/ipfs/ipfs-cluster.(*Cluster).Alerts()
      /home/iand/wip/iand/ipfs-cluster/cluster.go:395 +0x64
  github.com/ipfs/ipfs-cluster.TestClusterAlerts()
      /home/iand/wip/iand/ipfs-cluster/ipfscluster_test.go:2159 +0x238
  testing.tRunner()
      /opt/go/src/testing/testing.go:1194 +0x202

Previous write at 0x00c029ae7f10 by goroutine 5062:
  github.com/ipfs/ipfs-cluster.(*Cluster).alertsHandler()
      /home/iand/wip/iand/ipfs-cluster/cluster.go:429 +0x48c
  github.com/ipfs/ipfs-cluster.(*Cluster).run.func5()
      /home/iand/wip/iand/ipfs-cluster/cluster.go:596 +0x76

Goroutine 4785 (running) created at:
  testing.(*T).Run()
      /opt/go/src/testing/testing.go:1239 +0x5d7
  testing.runTests.func1()
      /opt/go/src/testing/testing.go:1512 +0xa6
  testing.tRunner()
      /opt/go/src/testing/testing.go:1194 +0x202
  testing.runTests()
      /opt/go/src/testing/testing.go:1510 +0x612
  testing.(*M).Run()
      /opt/go/src/testing/testing.go:1418 +0x3b3
  github.com/ipfs/ipfs-cluster.TestMain()
      /home/iand/wip/iand/ipfs-cluster/ipfscluster_test.go:134 +0x7dc
  main.main()
      _testmain.go:179 +0x271

Goroutine 5062 (running) created at:
  github.com/ipfs/ipfs-cluster.(*Cluster).run()
      /home/iand/wip/iand/ipfs-cluster/cluster.go:594 +0x1f6
  github.com/ipfs/ipfs-cluster.NewCluster.func1()
      /home/iand/wip/iand/ipfs-cluster/cluster.go:208 +0xa4
==================
--- FAIL: TestClusterAlerts (8.69s)
    testing.go:1093: race detected during execution of test
---
 cluster.go | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/cluster.go b/cluster.go
index 67c56654..276c2d3d 100644
--- a/cluster.go
+++ b/cluster.go
@@ -45,9 +45,7 @@ const (
 	maxAlerts           = 1000
 )
 
-var (
-	errFollowerMode = errors.New("this peer is configured to be in follower mode. Write operations are disabled")
-)
+var errFollowerMode = errors.New("this peer is configured to be in follower mode. Write operations are disabled")
 
 // Cluster is the main IPFS cluster component. It provides
 // the go-API for it and orchestrates the components that make up the system.
@@ -322,7 +320,6 @@ func (c *Cluster) pushInformerMetrics(ctx context.Context, informer Informer) {
 		}
 
 		metric, err := c.sendInformerMetric(ctx, informer)
-
 		if err != nil {
 			if (retries % retryWarnMod) == 0 {
 				logger.Errorf("error broadcasting metric: %s", err)
@@ -392,9 +389,8 @@ func (c *Cluster) pushPingMetrics(ctx context.Context) {
 // Alerts returns the last alerts recorded by this cluster peer with the most
 // recent first.
 func (c *Cluster) Alerts() []api.Alert {
-	alerts := make([]api.Alert, len(c.alerts))
-
 	c.alertsMux.Lock()
+	alerts := make([]api.Alert, len(c.alerts))
 	{
 		total := len(alerts)
 		for i, a := range c.alerts {
@@ -833,7 +829,7 @@ func (c *Cluster) ID(ctx context.Context) *api.ID {
 
 	id := &api.ID{
 		ID: c.id,
-		//PublicKey:          c.host.Peerstore().PubKey(c.id),
+		// PublicKey:          c.host.Peerstore().PubKey(c.id),
 		Addresses:             addrs,
 		ClusterPeers:          peers,
 		ClusterPeersAddresses: addresses,
@@ -1148,7 +1144,6 @@ func (c *Cluster) localPinInfoOp(
 	}
 	// return the last pInfo/err, should be the root Cid if everything ok
 	return pInfo, err
-
 }
 
 // RecoverAll triggers a RecoverAllLocal operation on all peers.